Preparation of organosilicon halides



Patented Aug. 28, 1945 NITED S ATES PATENT" or-rice it PREPARATION orORGANOSILICON' V muons Eugene G. Rocliow and William F. Gilliam,Schenectady, N. Y., assignors to General Electrlc Company, acorporatlon'ot New York No Drawing. Application July 26, 1943,

Serial No. 496,186

14 Claims. (Cl.260607) This invention relates to contact massescomprising silicon and an oxide of copper and to the use of such massesin the preparation of organosilicon halides from hydrocarbon halides. 1It is particularly concerned with the production of friable,oxidizedalloys of silicon and copper especially adapted to be employedin, effecting reaction between thesilicon component of the oxidizedalloy and a hydrocarbon halide in liquid or vapor state.

The copending application of Eugene G. Rochow, Serial No. 412,459, filedSeptember 26, 1941, discloses and claims a method of preparingorganosilicon halides, more particularly hydrocarbon-substituted siliconhalides, which comprises efiecting reaction between silicon and ahydrocarbon halide'in ,thepresence or absence of a metallic catalyst. Ifacatalyst isemployed,

it may be in the formof a finely-divided powder intimately associatedwith the silicon or in the form of an alloy of, the catalystmetalvwiththe silicon. ,The copending application of Eugene are notfully known or understood. However, from a comparison ofthetreatedalloys with the silicon-copper oxide mixtures in their reactions withhydrocarbon halides to form organosilicon halides, we are led to believethat the reactions invol'vedwhen the alloys are exposed to anoxidizingatmosphere include at least a partial oxidization of the copperand that the resultant xides are-present in. the friable product; Boththe silicon-copper oxide mixtures and-the.,;oxygen-treated, i. e.,.oxidized, alloys are very re- 'active with hydrocarbon halides.Larger,=yields G. Rochow and Winton I. Patnode, Serial -No.

412,460, filed September 26, 1941; describes and claims a method ofpreparing hydrocarbon-substituted silicon halides, e. g., methyl siliconchlorides, wherein is utilized a solid, porous contact mass of the kinddisclosed and claimed in the copending application of Winton I. Patnode,Se-

rial No. 412,461, filed September 26, 1941. These.

solid, porous contact masses preferably are obaralkylandalkaryl-halides, particularly' of organo-silicon halides, for example,phenyl silicon halides,-have consistently been obtained by employing anoxidized alloy in placeaol-g the fresh alloy.

The hydrocarbon halides used in thepprepiaration of organosiliconhalides in accordancetwit the present invention are the alkyl-J aryl;,th chlorides and bromides. Any of these; compounds when brought intointimate contact :with; the heated contact masses of our inventionqreact,with the silicon component thereof to form a -'mixture comprising thecorresponding hydrocarbon-substituted silicon halides; During th ereaction, some of the oxides of copper Lpossibly undergo a partialreduction in view. of. the vfact tained by firing underv reducingconditions a molded mixture of silicon and a powdered metallic catalystfor the reaction between silicon and a hydrocarbon halide. All of theabovementioned applications are assigned to the same assignee as thepresent invention.

- nized -by the fact that the intergranular oxidation greatly lessens'the cohesion of the cast mass,

rendering it easily pulverizable. The specific reactions involved andthe compounds formed 'durthe reactor in which the rzareiitoflbe' sed ingthe conversion of such alloys to a friable state that some water ispresent in the products of reaction first to beformedwhens'theinhydrocar- .bon halide is passed over theecheated contactmass. However, the formationsotaiwatericeases within-a short time andmicroscopic examination of'the powder after prolongedexposure'ita'methyl 35 chloride at the reaction temperatuie's'lha'slittle orno free copperin the mixture...

The contact masses consistin" BGSSEIltl ytof mixtures of silicon and acopper xide fareiiordinarily prepared by thoroughlysmixingcttheztwopowdered components inc? suitable'sproppl ns.

The resultant powder may briused or able size and shape, depending inn"he esignf of The pelletedor granular masse sometime at passage of thehydrocarbon ilialides is-particiilarly desirable.

The contact mas the oxidiz'edalloys a granular state and suitablecopper-silicon a mosphere for a peri d to convert the allo' a statewhere it i sii fi 1x.

liy crushed between the fingers.v For best results the friable alloy,preferably in the disintegrated state, is subjected to further oxidationto obtain maximum reactivity thereof with the hydrocarbon halides. Thisoxidation treatment may be rccomplished by exposing the alloy to air orto fizzy other oxygenous atmosphere at room temperature or at elevatedtemperatures. As the oxidation or agingat room, temperature requireslong periods of time measured in months or years, we prefer to carry outthe converslon at elevated temperatures, for example at temperatures inmethyl chloride passed over the heated charge at the rate of 2.25 g. perhr. Methyl chlorosilanes (methyl silicon chlorides) were formed at therate of 1.31 g. per hr. at first, but this rate decreased with time.When the reaction had 'almost ceased, about 3.7 per cent of the siliconhad been consumed at an overall rateof 0.142 gram per hour. v

(B) The same glass tube as was used in part (A) was charged with pelletsprepared from a ball-milled mixture of parts cuprous oxide with 90 partssilicon. The contact mass was heatthe neighborhood of 100 degrees to 350degrees C. At such elevated temperatures, the conversion of the alloy toa friable state is substantially completed in from one to two days,after which the friable material is preferably subjected-to furtherheating at these temperatures in an oxidizing atmosphere, for examplefor from 5 to 30 hours.

In order that those milled in the art better may understand how thepresent invention may be carried into eilect, the following illustrativeexamples are given:

Example 1 A hard. brittle commercial 50 per cent coppersilicon alloy washeated in an oven to 155 degrees C. for 20 hours. At the end or thistime the alloy was sufllciently friable to be broken up easilrand packedinto a glass reaction tube. The material was then further oxidized inthe tube by passing l'armtple 2 Some fresh 50 per cent silicon-copperalloy was reduced to small lumps in'a jaw crusher and placed in anair-circulating oven for 20 hours at I 155 degrees C. The resultantproduct then was pulverized. A glass reaction tube was charged with thepulverized material and the vapor of monochlorobenzene passed throughthe charge heated to a temperature of 420 degrees C. The first reactionproduct contained about '7 per cent of phenyl-silicon chlorides. Thecontact mass was then further oxidized for 16% hours at 305 to 340degrees C. 'by passing air through the mass in the reaction tube.Monochlorobenzene was again passed through the tube. The products ofreaction were found to contain about 20 per cent phenyl siliconchlorides. These results show the pronounced effect of the oxidationtreatment on the reactivity of the silicon-copper alloys and indicatethat maximum reactivity of the alloy is obtained by continuing theoxidation treatment beyond the point where the original alloy is firstconverted to a friable state.

Example 3 The catalytic eflect of the oxides of copper on the reactionwith-heated silicon of hydrocarbon halides, specifically methylchloride, is shown by the following examples:

\ (A) A glass reaction tube was charged with pressed powdered commercialsilicon. The charge was heated to a temperature of 300 degrees C. and

ed to a temperature of 300 degrees C. and methyl chloride passed throughthe heated mass at the rate of 225g. per hour. Methylsilicon chlorideswere formed at the rate of 2.25 grams per hour.

(C) Cupric oxide was substituted for the cuprous oxide employed in part(B). Employing the same reaction temperature and rate of flow of methylchloride, methyl silicon chlorides were produced at the rate of 3.87gms./hr. v

It will be understood, of course, by those skilled in the art that ourinvention is not limited to the specific hydrocarbon halides named inthe above illustrative examples and that any other hydrocarbon halidesmay be employed as reactants with,

the silicon, the conditions of reaction generally being varied,depending upon the particular starting hydrocarbon halide and theparticular end-products desired to be obtained.

Likewise-the invention is not limited to the specific reactiontemperatures or temperature ranges mentioned in the examples. However,the reaction temperature should not be so hi h as to cause an excessivedeposition of carbon upon the unreacted silicon during the reaction. Ingen- .eral. the reaction temperature to be used will vary with. forexample, the. particular hydrocarbon halide employed, the particularoxidized catalyst used and the yields of the specific reaction productsdesired to be obtained from a particular starting hydrocarbon halide.For example, by varying the temperature of reaction within thetemperature range of, say. 200 to 500 C., the proportions of theindividual products obtained when the hydrocarbon halide is brought intocontact with the contact mass can be varied, and also, the overall rateof reaction. At temperatures of about 200 C. the reaction'proceeds muchmore slowly than at reaction temperatures around 250 to 400 C. Attemperatures much above 400' C.. inthe case of methyl chloride forexample, there is a vigorous exothermic reaction which generally resultsin an undesirable deposition of 'carbon on the contact mass, therebylessening its emciency.

The oxide contact masses used in the practice of this invention may alsobe prepared from copper salts such as the nitrates which are readilyconverted to oxide. Ordinarily the copper oxide may comprise from 5 to60 per cent of the contact mass. We prefer to employ masses containingfrom- 10 to 50 per cent by weight of oxide or those prepared byoxidizing silicon-copper alloys containing from 10 to 50 per centcopper.

The present invention provides a new and improved method for theproduction of alkyl s11- icon halides (e. g., methyl, ethyl, propyl,butyl, amyl. isoamyl, hexyl, etc., silicon halides), the

- aryl silicon halides (e. g., phenyl silicon halides.

etc), the aryl-substituted aliphatic silicon halides (e. g., phenylethylsilicon halides, etc.) and the aliphatic-substituted aryl silicon halide(e. g., tolyl silicon halides, etc.).

The products of this invention have utility as intermediates in thepreparation of other products. For instance, they may be employed asstarting materials for the manufacture of silicone resins. They also maybe used as agents for treating water-non-repellent bodies to make.

silicon component of a contact mass comprising silicon and an oxide ofc( oper.

2. The method of preparing organosilicon halides which compriseseflecting reaction .between a hydrocarbon halide and a friable, oxidizedalloy of silicon and copper obtained by subjecting the alloy to anoxidizing atmosphere at a. temperature not exceeding about 350 C., thesaid hydrocarbon halide being selected from the group consisting ofalkyl, aryl, alkaryl, and aralkyl halides. I

3. The method of preparing alkyl silicon halides which comprisesefiecting reaction between an alkyl halideand the silicon component of acontact mass consisting of a mixture of pow dered silicon and a copperoxide.

4. The method. of preparing aryl silicon halides whichcomprises'efiecting reaction between an aryl halide and the siliconcomponent of a contact mass obtained by subjecting an alloy of siliconand copper containing from to 50 per cent copper to an oxidizingatmosphere at a temperature not exceeding about 350 C. until the alloyis converted to at least a friable state.

halides which comprises eflecting reaction between mono-halogenatedbenzene and the siliconcomponent of a contact'mass obtained by oxidizinga 50-50 alloy of silicon and copper by contacting said alloy with anoxidizing atmosphere at a temperature in the neighborhood of from 100 to350 C. until the alloy is converted at least to a friable state.

6. The method of preparing aryl silicon halides which compriseseifecting reaction between an aryl halide in the vapor state and thesilicon component of a contact mass consisting of an oxidized alloy ofequal parts by weight of silicon and copper obtained by heating saidalloy to a temperature of from 100 to 350 C. in an v 5. The method ofpreparing phenyl silicon cient to convert the alloy to at. least afriable state.

'7. The method of preparing aryl silicon chlorides which compriseseffecting reaction between an aryl chloride in a vapor state and thesilicon component of a contact mass obtained by heating a 50-50copper-silicon alloy in air for at least hours at a temperature of 155C.

8. The method of preparing methyl silicon halides which compriseseffecting reaction between a methyl halide and the silicon component ofa partially oxidized silicon-copper alloy obtained: by heating saidalloy to a temperature not exceeding about 350 C. for a period of timesuflicient to convert the alloy to at least a friable state.

9. The method of producing a contact mass adapted to be used ineflecting chemical reaction between silicon and a hydrocarbon halidewhich comprises'oxidizing an alloy of silicon and copper at atemperature not exceeding about 350 c. to at leasta friable state.

10. The'fiiethod of producing a contact mass adapted to be used ineffecting chemical reac tion between silicon and an aryl halide whichcomprises contacting an alloy of silicon and copper with an oxidizingatmosphere at a temperature not exceeding about 350 C. fora period oftime sufflcient to convert said alloy to a friable state, crushing thefriable alloy to a 'finely-' divided state and subjecting thefinely-divided material to further oxidation at an elevated Itemperature not exceeding about 350 C.

oxidizing atmosphere fo'r'a period of time sufli- 11. The method as inclaim 10- wherein the finely-divided, friable alloy is subjected tofurther oxidation for from 5 to 30 hours at a temperature between and350degrees C.

12. A contact mass adapted to be used in effecting chemical reactionconsisting of silicon and an oxide of copper as essential ingredients.'

13. A contact mass adapted to be used in effecting chemical reactionbetween silicon and a hydrocarbon halide, said mass consisting of anoxidized copper-silicon alloy obtained by contacting said alloy with anoxidizing atmosphere at a temperature not exceeding about 350 C., thesaid alloy being oxidized to at least a friable state. 14. Afinely-divided contact mass adapted to be used in efl'ecting chemicalreaction betwee silicon and an aryl halide, said mass consisting of anoxidized, friable, silicon-copper alloy containing from 10 to 50 percent copper, the said oxidized alloy being obtained by heating thesilicon-copper alloy to a temperature in the v neighborhood of from 100to 350 C.

EUGENE G. ROCHOW. W ILLIAM F. GILLIAM.

